The rail line down the west side of Manhattan into Penn Station is currently Amtrak only. It branches off the Metro-North Hudson Line at Spuyten Duyvil (I apologize if I misspelled the name) and crosses the Harlem River on a drawbridge. Because of the New York city law that restricts locomotive use on the island, Amtrak trains on this route use dual-mode P32s exclusively. These diesel/electric versions of the GE Genesis locomotive are the successors to Amtrak's small stable of ex-New Haven FL9s that it inherited from Penn Central/Conrail.

Routing some Metro-North services down this line into Penn Station is actually a good idea whose time may yet come. Since the Metropolitan Transportation Authority operates both M-N and LIRR services, they could actually through-route trains between Hudson Line stations north of the city and destinations on Long Island, and do so long before the East Side Access is complete.